Method of casting abrasive-faced articles



Jan. 10, 1933. R. s. EDMONDSON ET AL 1,893,539

METHOD OF CASTING ABRASIVE FACED ARTICLES Filed Dec. 11, 1930 4/6 Z2514. f v /////%////////////%/%%/%/////x aw INVENTORS 9 a m/ w ATT RNEX ,S

Patented Jan. 10, 1933 UNITE]? STATES PATENT OFFICE- RALPH'. S. EDMONDSON, OF ELIZABETH, AND MATHEW HOLMES, OF HILLSIDE, NEW JERSEY, ASSIGNOBS TO AMERICAN ABBASIVE METALS COMPANY, A CORPORATION 0! NEW YORK IIE'I'EOD OF CASTING ABBASIVE-FACED ABTIGLES Application filed December 11, 1930. Serial No. 501,665.

resistant surfaces ada ted to resist abrasion,

such as stair treads, oor plates, ash chutes, paddle blades for mills, trench or gutter covers and the like, wherein bodies or grams of hard, wear-resistant material are embedded in a metal body or casting so as to be exposed on the surface thereof.

A Well known method of making such castings is set forth in U. S. patent to Bowers, No. 1,403,005; and, as there described, said method includes providing a green sand mold and coating a surface of the mold, which is to give form to the protective surface of the casting, with a layer of finely divided or powdered material. On this material, which will act as a holding bed for the same, are distributed grains of hard wear-resistant material which are to form the protective or wear-resistant face of the casting. These grains may be of emery, carborundum, alundum, or other hard mineral substance which will not fuse at the temperature of the molten metal forming the casting.

The molten metal, generally cast iron, is poured into the mold, and the grains of wear-resistant material, which are held from displacement by the bed of finely powdered material, are surrounded by and embedded in the metal of the casting and form thereon a wear-resistant surface.

The holding bed for the wear-resistant grains may be made of a material which will fuse with the molten metal and have no influence or effect upon the surface of the casting, but preferably an infusible mineral substance, as fire clay, or a material which will be consumed or dissipated by the heat of the molten metal, as rye flour, is used. The dried material of the holding bed will absorb moisture from the green sand in the mold and thus acquire in some degree a capacity to hold the hard or wear-resistant particles against displacement by the flow of the molten metal, and the hard grains will become embedded in the metal of the casting, although in some instances the bed is sprinkled with water. Further, by reason of the moist character of the mold surface, the holding bed of finely powdered material will tend to adhere thereto and consequently the powdered material can be readily applied to vertical and irregularly shaped or overhanging mold surfaces.

This method of making metal castings having surfaces adapted to resist abrasion, while thoroughly practical, fails of perfection however, in that for example during the pouring of the molten metal into the mold some of the grains of the wear-resistant material will be shifted from their original positions in the holding bed and bring about an uneven distribution of thegrains, thus causing unnecessary crowding of the grains in some places on the protective surface of the casting and insufficient supply of them in other places on said surfaces. Especially is this true of the grains which lie on top of other grains and form second and third layers of the grains. Also, there sometimes happens a shifting of particles of the holding bed with reference to the mold, resulting finally in an uneven distribution of the grains of hard wear-resistant material in the finished casting. This uneven distribution of the grains produces an ineflicient casting.

The object of the invention, therefore, is to provide an improved method of making castings of the character described, in the exercise of which method no shifting of the wear-resistant grains will take place and likewise no shifting of the holding bed for the wear-resistant grains will occur with relation to the mold surface upon which such bed rests, nor any shifting of the particles of the bed with relation to 'each other.

To bring about the desired results, the holding bed and the wear-resistant grains are treated in such manner, in accordance with the teachings of the invention, that the wear-resistant grains are secured firmly to the holding bed and the individual contacting grains to each other; and there is formed a thoroughly coherent mass of the holding bed, the powdered particles of which are now firmly united to each other, and the underlying particles of which are positively attached to the green sand of the mold.

In the accompanying drawing, which forms part hereof, is illustrated a mold formed according to the invention.

Of the drawing:

Fig. 1 is a cross-section of a mold adapted for wasting an article in accordance with the method of this invention;

Fig. 2 is a fragmentary view of the same, on an enlarged scale and showing the application of the water glass;

Fig. 3 is a similar view after the water glass has been applied and showing the application of the blow torch; and

Fig. 4 is a sectional view of a part of the finished article, cast according to the method of the invention.

Referring to the drawing in detail, there is shown in Fig. 1 a mold 4, comprising a drag 5 and cope 6 which are formed to mold a wear-resistant article, as a stair tread 7 On a surface 8 of the green sand of the mold 4 is laid the holding bed 9, preferably formed of fireclay, in which are strewn the wearresistant grains 1().

The first step in this treatment is taken preferably after the wear-resistant grams have been strewn over the holding bed, and consists in spraying the wear-resistant grains and their holding bed with a liquid 11 which has the adhesive or Viscous attribute necessary to accomplish the union of the holding bed particles, sand mold, and the wear-resistant grains, as described, and which at the same time possesses the fluidity required to permit it to be sprinkled or applied efiiciently to the grains and their holding bed. The viscous liquid, like the material of the holding bed, must also be of such a nature that it will have no influence or effect upon the surface of the casting and therefore, it may comprise infusible matter or matter which will be fused with the molten metal poured into the mold or be consumed or dissipated thereby. The molten metal enters the mold through the gate 12 and flows over and about the grains 10 and thus forms the body 13 of the tread with its resistant surface 14, as shown in Fig. 4.

It will be apparent that a liquid, possessing the viscosity or adhesiveness necessary for the purpose set forth will not possess the required fluidity; and, therefore, the viscous liquid to be used should be one that can be readily diluted with some other liquid having the necessary fluidity, furthermore, the blended liquids should be of such nature that the diluent can be removed from the resulting compound after the sprinkling process therewith has been completed. It is also important that these liquids should be comparatively inexpensive so as to be commercially possible.

Specifically, according to the invention, a neutralized and concentrated sulphite liquor of thesulphite paper pulp process, carrying the soluble vegetable resins of wood, together with other soluble vegetable compounds, and hereinafter referred to as sulphite liquor, supplies fully the adhesive or viscous uality required in the liquid. Sulphite liquor, while itself economical, has the further advantage that -it is miscible with water, a quality lacking from some other substances which might otherwise be used. Water, furthermore, is the cheapest and most common diluent. After the wear-resistant grains have been distributed on the holding bed, therefore, the bed and grains are sprinkled with sulphite liquor which has been diluted with water to the extent necessary for permitting sprinkling. The diluted sulphite liquor will penetrate between the particles of the holding bed and cause them to adhere firmly v to the face of the mold and to each other, and will likewise cause the wear-resistant grains to adhere firmly to the holding bed and, when contacting, with each other.

After the application of the liquid compound to the grains and their holding bed, it is desirable to remove the water content from the compound before the molten metal comes into direct contact therewith, as otherwise the water, under the influence of the heat, might cause blowing of the mold, resulting in possible distorted castings, if not dangerous consequences, due to the flying up of molten metal from the pouring gates ofthe mold. Some substances, otherwise available, cannot be used in place of sulphite liquor because the water cannot be thoroughly separated from them. The water, however, is readily and thoroughly removed from the sulphite liquor compound by applying heat thereto, as by means of a blow torch, which application of heat comprises the preferred and specific form of the next step in the improved method of the present invention. It is to be noted that if fire clay, which is preferably used for the holding bed in the present process, be dried or baked by the application of heat thereto without first applying thereto a suitable binder as ,a viscous liquid, such as sulphite liquor, it will lose its holding power and will not retain the wearresistant grains in place. By first applying the sulphite liquor, however, in a compound in the manner indicated, the heat of the torch can then be applied and not only will the water be evaporated from the sulphite liquor compound but the fire clay and sulphite liquor will be baked or dried to form a composite mass in which the wear-resistant grains are firmly held, and the fire clay will be firmly secured to the face of the mold. The residue of the sulphite liquor left after the application of the heat acts as a glue or cement which effectively anchors the wear-resistant grains and the holding body to the mold and prevents the washing away of the grains by the inflowing stream of molten metal or the moving of the holding bed or its component particles by the stream. Also, the residue is nonexplosive upon the application of heat, and in the combustion or dissipation of the sulphite liquor no gases are created which would surround the grains of wear-resistant material and prevent the close grip of the same by the metal of the body of the casting. These are valuable features and are lacking from some substances which might otherwise be available for use in this connection. After drying the sulphite liquor as described, the molten metal is poured into the mold and the casting operation completed. It will be seen that the method of casting articles adapted to resist abrasion as heretofore described, carries out the object of the invention as stated, besides possessing other advantages which will be apparent to those skilled in the art.

The invention is not limited to the precise number or sequence of steps, or to the use of the particular materials described, as changes may be made therein without departing from the spirit of the invention or sacrificing any of its chief advantages. For example, a variation from the particular method hereinbefore described consists in spraying the holding bed with the diluted sulphite liquor, sprinkling fine grains of the hard wear-resistant material over the holding bed, spraying again with the diluted sulphite liquor, and then sprikling a layer of coarser grains of the hard wear-resistant material. This and other variations will readily suggest themselves to those skilled in the art now that the present process has been disclosed.

Having thus described our invention, what we claim is:

1. The method of forming a metal casting having a wear-resistant surface, .which method comprises providing a mold, applying to a mold surface thereof, which is to give form to the wear-resistant surface of the casting, a layer composed of particles of holding material to form a holding bed for the wear-resistant materials, distributing grains of a wear-resistant material over said bed, applying to said bed and grains a viscous or adhesive liquid compound, drying said compound, and introducing molten metal into the mold.

2. In the method of forming a metal casting having a wear-resistant surface, which includes providing a mold, applying to a mold surface thereof, which is to give form to the wear-resistant surface of the casting, a layer composed of particles of holding material to form a holding bed for'the wearresistant materials, and distributing grains of a wear-resistant material over said bed. the improved step of spraying said bed and grains with a viscous or adhesive liquid compound rendered fluid by the admixture therewith of a diluent.

3. The method of forming a metal casting having a wear-resistant surface, which method comprises providing a mold, applying to a mold surface thereof, which is to give form to the wear-resistant surface of the casting, a layer composed of particles of holding material to form a holding bed for the wear-resistant materials, distributing grains of a wear-resistant material over said bed, spraying said bed and grains with a viscous or adhesive liquid compound rendered fluid by the admixture of water therewith, drying the bed, and introducing molten metal into the mold.

4. The method of forming a metal casting having a wear-resistant surface, which method comprises providing a mold, applying to a mold surface thereof, which is to give form to the wear resistant surface of the casting, a layercomposed of particles of holding material to form a holding bed for the wear-resistant materials, distributing grains of a wear-resistant material over said body, spraying said bed and grains with sulphite liquor diluted by the admixture of water therewith, drying the bed, and introducing molten metal into the mold.

5. The method of forming a metal casting having a wear-resistant surface, which method comprises providing a mold, applying to a mold surface thereof, which is to give form to the wear-resistant surface of the casting. a layer of infusible material in a powdered form to form a holding bed for the wear-resistant materials, distributing grains of wear-resistant material over said bed. spraying said bed and grains with sulphite liquor diluted by the admixture of water therewith, driving off the water from the sprayed sulphite liquor, and introducing molten metal into the mold.

6. The method of forming a metal casting having a wear-resistant surface, which method comprises providing a mold, applying to amold surface thereof, which is to give form to the wear-resistant surface of the casting, a layer of material in powdered form adapted to be dissipated by the heat of the molten metal poured into the mold, said material forming a holding bed for the wear-resistant material, distributing grains of wear-resistant material over said bed, spraying said bed and grains with sulphite liquor diluted by the mixture of water therewith, evaporating said water. and introducing molten metal into the mold.

7. The method of forming a metal cast grains with sulphite liquor diluted by the admixture of water therewith, drying the bedl,d and introducing molten metal into the mo 8. In the method of forming a metal casting having a wear-resistant surface, which includes providing a mold, applying to a mold surface thereof, which is to give form to the wear-resistant surface of the casting, a layer composed of articles of holding material to form a ho ding bed for the wear-resistant materials, and distributing grains of a wear-resistant material over said bed, the improved step of appl ing to said bed and grains a neutralized an concentrated sulphite liquor of the sulphite paper pulp process, carrying the soluble vegetable resins of wood.

9. In the method of forming a metal casting having a wear-resistant surface, which includes providing a mold, applying to a mold surface thereof, which is to give form to the wear-resistant surface of the casting, a layer composed of particles of holding material to form a holding bed for the wear-resistant materials, and distributing grains of a wear-resistant material over sa1d bed, the improved step of applying to said bed and grains a sulphite liquor, carrying vegetable compounds.

10. The method of forming a metal casting having a wear-resistant surface, which method comprises providing a mold, applying to a mold surface thereof, which is to give form to the wear-resistant surface of the casting, a layer composed of particles of holding material to form a holding bed for the Wear-resistant materials, distributing grains of a wear-resistant material over said bed, applying to said bed and grains a neutralized and concentrated sulphite liquor of the sulphite paper pulp process, carrying the soluble vegetable resins of wood, drying the bed, and introducing molten metal into the mold.

In testimony whereof, this specification has been duly signed by:

RALPH S. EDMONDSON. MATHEW HOLMES. 

